Ellipsometric study of polycrystalline silicon films prepared by low-pressure chemical vapor deposition

Polysilicon layers with thicknesses between 8 and 600 nm deposited by low-p ressure chemical vapor deposition at temperatures ranging from 560 to 640 d egrees C were characterized by spectroscopic ellipsometry (SE) to determine the layer thicknesses and compositions using multilayer optical models and the Bruggeman effective-medium approximation. The dependence of the struct ural parameters on the layer thickness and deposition temperature have been investigated. A better characterization of the polysilicon layer is achiev ed by using the reference data of fine-grained polysilicon in the optical m odel. The amount of voids in the polysilicon layer was independently measur ed by Rutherford backscattering spectrometry (RBS). The SE and RBS results show a good correlation. The comparison of the surface roughness measured b y SE and atomic force microscopy (AFM) shows that independently of the AFM window sizes, a good correlation of the roughness determined by SE and AFM was obtained. (C) 2000 American Institute of Physics. [S0021-8979(00)01604- 2].